40 ORGANIC EVOLUTION — PHYSICAL 



it more than others ; yet many of the cells of all 

 portions of the whole organism are capable of perform- 

 ing it, for almost any fragment of a sponge, if separated 

 from the parent mass and bedded out, is capable of grow- 

 ing into an "individual " and of continuing the race. If 

 we pass in succession to higher species, we find cell- 

 specialization becoming more and more marked ; we 

 find cells becoming more and more capable of perform- 

 ing efficiently some one function and less and less 

 capable of performing all other functions. A division 

 of labour thus occurs in the cell-community similar 

 to that which distinguishes communities of civilized 

 men from savage communities. Every savage does 

 everything for himself, receiving small help from the 

 rest of the community and giving little in return ; and 

 the more utterly savage the community is, the more 

 complete in general is the independence of the indi- 

 vidual. But while the savage performs all the labours 

 necessary for supporting life, he performs each one less 

 efficiently than he would did he devote himself entirely 

 to it. In civilized communities each man devotes him- 

 self to some special work which he performs specially 

 well, but which would not enable him to live unless it 

 were supplemented by the labours of other men, who 

 ia like manner perform other special duties equally 

 well. Thus a bricklayer performs a special duty better 

 than he could do were he also a carpenter, a farmer, and 

 a miner ; but except he receive help from the labours of 

 others his work does not produce all that he requires 

 to maintain life. It is not, for instance, directly pro- 

 ductive of food and clothing. For these he depends on 

 the labours of other specialists ; and therefore the higher 

 the state of civilization the more complete is the state 

 of interdependence of the members of the community. 



So in higher animal organisms we find that all cells 

 have taken up special duties — have all become specialists. 



